144 THE CANADIAN ENTOMOLOGIST. 



as before stated, had died at its post, where it was held by the inserted 

 ovipositor. 



Here, unfortunately, our observations end, and we can only form con- 

 jectures as to the life of the larvte. Provancher remarks of the genus 

 that, " Their larv?e live as parasites in the body of other larvsv ";'' and with 

 reference to ensiger, he says : " We have frequently met this insect in com- 

 pany of Braconids, upon trunks of dead fir-trees, searching without 

 doubt to deposit its eggs in the body of lignivorous larva?." His authority 

 for the first statement is not given, but probably he has accepted the con- 

 jecture of some European Entomologist. 



Prof Riley has demonstrated, in the case of Thalessa, how unsafe it 

 is to accept conjecture as fact, however probable it may seem. Still, in 

 the absence of a complete knowledge of an insect's life, one must often 

 fill in by conjecture the missing links, and wait for further investigations 

 to prove their value. As regards Ibalia viandipennis, there are two ways 

 in which the larva? may live, viz., either directly upon the dead, or decay- 

 ing woody tissues of the tree, or in or upon the bodies of larva? which do 

 so subsist. 



The former course seems less probable, and I am inclined to think 

 with those who believe that it is parasitic upon lignivorous larvse. What 

 species, then, is it likely to be parasitic upon ? The maple trees upon 

 which it occurs are badly infested by Tremex colutnba, Xiphydria 

 albicornis and Dicerca divaricata, and in a less degree by other insects. 

 The beech trees are also infested by the Tremex and Dicerca, and like 

 the maples are much frequented by Thalessa. Is Ibalia parasitic upon 

 its Hymenopterous (closely connected) relatives, or upon the Coleoptera ? 



Now that its time and place of occurrence are known, I hope that its 

 history may soon be worked out in full. Its season of appearance is 

 apparently brief, as all the specimens from this locality have been taken 

 in June — the earliest upon the loth, and the latest on the 28th. The 

 insect might thus readily escape notice, even when not rare, as they are 

 by no means conspicuous, either when ovipositing or crawling upon the 

 rough trunks they frequent. But, if systematically searched for during 

 the month of June upon old trees, they would probably be found by 

 many of our entomologists. 



While not abundant, these insects cannot be classed as especially rare, 

 for besides the specimens mentioned in this note, I have seen several which 



